A study to determine chest wall vibratory attachment interface locations for a low frequency sonic vibrator in treatment of acute coronary thrombosis

Abstract

Our institution is developing a non-invasive Diastolic Timed Vibrator (DTV) to enhance emergency clearance of acute coronary thrombosis. Sonic frequency diastolic vibro-percussion (i.e. 50Hz, 2mm amplitude) applied upon the rib-spaces of the left sternal border has shown to improve left ventricular performance and coronary flow in human volunteers. However, therapeutic acoustic penetrability cannot be assumed depending on varying chest size and lung position which attenuates acoustic transmissions. Furthermore, chest locations enabling a direct lung free pathway overlying the base of the heart (wherein the coronaries arise) should be promoted, while locations overlying the left ventricular apex (site of potential thrombus formation) should be avoided. We therefore set out to determine preferred chest wall placement positions for a vibratory interface suitable for treatment of ST Elevation Myocardial Infarction (STEMI). Inter-Costal Space (ICS) positions to the left or right of the sternum were interrogated in 90 adults following routine Echocardiography to ascertain whether the base of the heart could be imaged (hence inferring acoustic transmissibility), and to determine over what part of the heart each transducer position was overlying. The third and fourth ICS proximate the left sternal border provided acoustic transmissibility in 96 and 100% of cases respectively, with only one unwanted occurrence from the fourth ICS where the transducer overlaid the apical third of the left ventricle. Acoustic transmissibility from third and fourth ICS right sternal border was documented in 53 and 85% of cases respectively. A vibration interface in STEMI treatment should allow for contact overlying the left and right third and fourth ICS generally proximate the sternal borders. As vibration transmission to the cardiac apex and/or left atrium cannot be completely avoided, vibration therapy should be contra-indicated in late presenters for antero-septal apical STEMI, and in cases of new onset atrial fibrillation persisting greater than 48h which have not been adequately anti-coagulated.